C# ADO EF - TPH 中派生类型之间的错误映射关联
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时间：2020-08-04 08:07:58 来源:igfitidea点击:
ADO EF - Errors Mapping Associations between Derived Types in TPH
提问by Zach Burlingame
Background
背景
I am writing a data access library using the ADO Entity Framework in Visual Studio 2008 SP1 using the .NET Framework 3.5 SP1. I am trying to create associations between two entities that are both derived from an abstract type. I am representing both entity inheritance hierarchies using Table Per Hierarchy(TPH) which means there are just two tables - one for each entity inheritance hierarchy.
我正在使用 .NET Framework 3.5 SP1 在 Visual Studio 2008 SP1 中使用 ADO 实体框架编写数据访问库。我试图在两个都从抽象类型派生的实体之间创建关联。我使用Table Per Hierarchy(TPH)表示两个实体继承层次结构，这意味着只有两个表 - 每个实体继承层次结构一个。
NOTEYou can use Table Per Type (TPT) to avoid this problem, but it comes with it's own drawbacks. See hereand herefor more details when choosing between inheritance persistence models.
注意您可以使用 Table Per Type (TPT) 来避免这个问题，但它有其自身的缺点。在继承持久性模型之间进行选择时，请参阅此处和此处了解更多详细信息。
Here is a screenshot of the Designer view of the Entity Model:
这是实体模型的设计器视图的屏幕截图：
And here is a screenshot of the database schema:
这是数据库架构的屏幕截图：
Assumptions
假设
When you create associations in the ADO Entity Framework Designer between derived types modeled with TPH using Visual Studio 2008 SP1 and the .NET Framework 3.5 SP1 you are likely to receive the following an "Error 3034: Two entities with different keys are mapped to the same row. Ensure these two mapping fragments do no map two groups of entities with overlapping keys to the same group of rows."
当您在 ADO 实体框架设计器中使用 Visual Studio 2008 SP1 和 .NET Framework 3.5 SP1 在使用 TPH 建模的派生类型之间创建关联时，您可能会收到以下“错误 3034：具有不同键的两个实体映射到相同行。确保这两个映射片段不会将具有重叠键的两组实体映射到同一组行。”
Based on what I have read online, in order to resolve this issue, you must add a Condition to the association on the Foreign Key like so:
根据我在网上阅读的内容，为了解决此问题，您必须向外键上的关联添加一个条件，如下所示：
<Condition ColumnName="Endpoint1" IsNull="false" />
Here's a screenshot of this edit for the PersonPersonToPerson1 association:
这是 PersonPersonToPerson1 关联的此编辑的屏幕截图：
Constraints
约束
- The base classes of each hierarchy (i.e. Node and Link) mustbe abstract.
- The navigation properties from the associations between two derived types mustbe distinguishable by link type (e.g. PersonToPerson and PersonToLocation). This means you cannotcreate the associations between the Link and Node abstract base classes.
- 每个层次结构（即节点和链接）的基类必须是抽象的。
- 来自两个派生类型之间关联的导航属性必须通过链接类型（例如 PersonToPerson 和 PersonToLocation）来区分。这意味着您不能在 Link 和 Node 抽象基类之间创建关联。
Problem:
问题：
When I create the Entity Model as described above and add the Conditions to the AssociationMappings as described in the Assumptions above, I receive an "Error 3023" when I build/validate the model.
当我如上所述创建实体模型并将条件添加到关联映射中时，如上述假设中所述，我在构建/验证模型时收到“错误 3023”。
Error 1 Error 3023: Problem in Mapping Fragments starting at lines 146, 153, 159, 186, 195, 204, 213: Column Link.Endpoint1 has no default value and is not nullable. A column value is required to store entity data.
An Entity with Key (PK) will not round-trip when:
((PK is NOT in 'LinkSet' EntitySet OR PK does NOT play Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson1') AND (PK is in 'LinkSet' EntitySet OR PK plays Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson1' OR PK plays Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson'))
C:\Documents and Settings\Demo\My Documents\Visual Studio 2008\Projects\GraphExample2.BusinessEntities\GraphExample2.BusinessEntities\GraphModel.edmx 147 15 GraphExample2.BusinessEntities
The thing that the Entity Framework is getting hung up on in the above scenario is that there are two properties being mapped on to the same foreign keys. For example, the column and foreign key for Endpoint1 is mapped to the Person property in the PersonToLocation derived type and it's mapped to the Leader property in the PersonToPerson derived type.
实体框架在上述场景中遇到的问题是有两个属性被映射到相同的外键。例如，Endpoint1 的列和外键映射到 PersonToLocation 派生类型中的 Person 属性，并映射到 PersonToPerson 派生类型中的 Leader 属性。
I don't understand why this is an issue. Since the Leader/Follower Properties are only in the PersonToPerson derived type - not any other derived type or base type - and the same is true of the Person/Location property, why isn't the TypeDiscriminator field sufficient for the EF to figure out which set a given row belongs in?
我不明白为什么这是一个问题。由于领导者/追随者属性仅在 PersonToPerson 派生类型中 - 而不是任何其他派生类型或基类型 - 而且 Person/Location 属性也是如此，为什么 TypeDiscriminator 字段不足以让 EF 找出哪个设置给定的行所属？
To me it seems like, if you are dealing with an object where TypeDiscriminator = 1, you place Endpoint1 in Leader and Endpoint2 in Follower. Likewise, if you are dealing with an object where TypeDiscriminator = 2, you place Endpoint1 in Person and Endpoint2 in Location.
在我看来，如果您正在处理 TypeDiscriminator = 1 的对象，则将 Endpoint1 放在 Leader 中，将 Endpoint2 放在 Follower 中。同样，如果您正在处理 TypeDiscriminator = 2 的对象，则将 Endpoint1 放在 Person 中，将 Endpoint2 放在 Location 中。
Question:
题：
How do you resolve the Error 3023 to allow these associations to occur ?
您如何解决错误 3023 以允许发生这些关联？
OR
或者
How do you create the type of associations in the ADO Entity Framework that I have described above?
您如何在我上面描述的 ADO 实体框架中创建关联类型？
References:
参考：
- MSDN Forum - Error 3034: Problem in Mapping Fragments starting at lines ...
- Zeeshan Hirani's Blog - Contributions to Entity framework community
- Zeeshan Hirani's Entity Framework learning guide(this is an Excellent 514 page step-by-step guide to numerous concepts and gotchas with ADO EF. HIGHLY recommended!)
- MSDN 论坛 -错误 3034：从行开始映射片段的问题......
- Zeeshan Hirani 的博客 -对实体框架社区的贡献
- Zeeshan Hirani 的实体框架学习指南（这是一个优秀的 514 页分步指南，介绍了 ADO EF 的众多概念和问题。强烈推荐！）
Code
代码
SQL:
查询语句：
USE [GraphExample2]
GO
/****** Object: Table [dbo].[Node] Script Date: 02/17/2009 14:36:13 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Node](
[NodeID] [int] NOT NULL,
[NodeTypeDiscriminator] [int] NOT NULL,
[Name] [varchar](255) NOT NULL,
[Description] [varchar](1023) NULL,
CONSTRAINT [PK_Node] PRIMARY KEY CLUSTERED
(
[NodeID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object: Table [dbo].[Link] Script Date: 02/17/2009 14:36:12 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Link](
[LinkID] [int] NOT NULL,
[LinkTypeDiscriminator] [int] NOT NULL,
[Endpoint1] [int] NOT NULL,
[Endpoint2] [int] NOT NULL,
[Name] [varchar](255) NULL,
[Description] [varchar](1023) NULL,
CONSTRAINT [PK_Link] PRIMARY KEY CLUSTERED
(
[LinkID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object: ForeignKey [FK_Link_Node_Endpoint1] Script Date: 02/17/2009 14:36:12 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Endpoint1] FOREIGN KEY([Endpoint1])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Endpoint1]
GO
/****** Object: ForeignKey [FK_Link_Node_Endpoint2] Script Date: 02/17/2009 14:36:12 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Endpoint2] FOREIGN KEY([Endpoint2])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Endpoint2]
GO
EDMX:
EDMX：
<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
<!-- EF Runtime content -->
<edmx:Runtime>
<!-- SSDL content -->
<edmx:StorageModels>
<Schema Namespace="GraphModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
<EntityContainer Name="GraphModelStoreContainer">
<EntitySet Name="Link" EntityType="GraphModel.Store.Link" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Node" EntityType="GraphModel.Store.Node" store:Type="Tables" Schema="dbo" />
<AssociationSet Name="FK_Link_Node_Endpoint1" Association="GraphModel.Store.FK_Link_Node_Endpoint1">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
<AssociationSet Name="FK_Link_Node_Endpoint2" Association="GraphModel.Store.FK_Link_Node_Endpoint2">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Link">
<Key>
<PropertyRef Name="LinkID" />
</Key>
<Property Name="LinkID" Type="int" Nullable="false" />
<Property Name="LinkTypeDiscriminator" Type="int" Nullable="false" />
<Property Name="Endpoint1" Type="int" Nullable="false" />
<Property Name="Endpoint2" Type="int" Nullable="false" />
<Property Name="Name" Type="varchar" MaxLength="255" />
<Property Name="Description" Type="varchar" MaxLength="1023" />
</EntityType>
<EntityType Name="Node">
<Key>
<PropertyRef Name="NodeID" />
</Key>
<Property Name="NodeID" Type="int" Nullable="false" />
<Property Name="NodeTypeDiscriminator" Type="int" Nullable="false" />
<Property Name="Name" Type="varchar" Nullable="false" MaxLength="255" />
<Property Name="Description" Type="varchar" MaxLength="1023" />
</EntityType>
<Association Name="FK_Link_Node_Endpoint1">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="Endpoint1" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Link_Node_Endpoint2">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="Endpoint2" />
</Dependent>
</ReferentialConstraint>
</Association>
</Schema>
</edmx:StorageModels>
<!-- CSDL content -->
<edmx:ConceptualModels>
<Schema xmlns="http://schemas.microsoft.com/ado/2006/04/edm" Namespace="GraphModel" Alias="Self">
<EntityContainer Name="GraphModelContainer" >
<EntitySet Name="NodeSet" EntityType="GraphModel.Node" />
<EntitySet Name="LinkSet" EntityType="GraphModel.Link" />
<AssociationSet Name="PersonPersonToPerson" Association="GraphModel.PersonPersonToPerson">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToPerson" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="PersonPersonToPerson1" Association="GraphModel.PersonPersonToPerson1">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToPerson" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="Person_PersonToLocation" Association="GraphModel.Person_PersonToLocation">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToLocation" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="Location_PersonToLocation" Association="GraphModel.Location_PersonToLocation">
<End Role="Location" EntitySet="NodeSet" />
<End Role="PersonToLocation" EntitySet="LinkSet" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Node" Abstract="true">
<Key>
<PropertyRef Name="NodeId" />
</Key>
<Property Name="NodeId" Type="Int32" Nullable="false" />
<Property Name="Name" Type="String" Nullable="false" />
<Property Name="Description" Type="String" Nullable="true" />
</EntityType>
<EntityType Name="Person" BaseType="GraphModel.Node" >
<NavigationProperty Name="Leaders" Relationship="GraphModel.PersonPersonToPerson" FromRole="Person" ToRole="PersonToPerson" />
<NavigationProperty Name="Followers" Relationship="GraphModel.PersonPersonToPerson1" FromRole="Person" ToRole="PersonToPerson" />
<NavigationProperty Name="Locations" Relationship="GraphModel.Person_PersonToLocation" FromRole="Person" ToRole="PersonToLocation" />
</EntityType>
<EntityType Name="Location" BaseType="GraphModel.Node" >
<NavigationProperty Name="Visitors" Relationship="GraphModel.Location_PersonToLocation" FromRole="Location" ToRole="PersonToLocation" />
</EntityType>
<EntityType Name="Link" Abstract="true">
<Key>
<PropertyRef Name="LinkId" />
</Key>
<Property Name="LinkId" Type="Int32" Nullable="false" />
<Property Name="Name" Type="String" Nullable="true" />
<Property Name="Description" Type="String" Nullable="true" />
</EntityType>
<EntityType Name="PersonToPerson" BaseType="GraphModel.Link" >
<NavigationProperty Name="Leader" Relationship="GraphModel.PersonPersonToPerson" FromRole="PersonToPerson" ToRole="Person" />
<NavigationProperty Name="Follower" Relationship="GraphModel.PersonPersonToPerson1" FromRole="PersonToPerson" ToRole="Person" />
</EntityType>
<EntityType Name="PersonToLocation" BaseType="GraphModel.Link" >
<NavigationProperty Name="Person" Relationship="GraphModel.Person_PersonToLocation" FromRole="PersonToLocation" ToRole="Person" />
<NavigationProperty Name="Location" Relationship="GraphModel.Location_PersonToLocation" FromRole="PersonToLocation" ToRole="Location" />
</EntityType>
<Association Name="PersonPersonToPerson">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
</Association>
<Association Name="PersonPersonToPerson1">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
</Association>
<Association Name="Person_PersonToLocation">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
</Association>
<Association Name="Location_PersonToLocation">
<End Type="GraphModel.Location" Role="Location" Multiplicity="1" />
<End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
</Association>
</Schema>
</edmx:ConceptualModels>
<!-- C-S mapping content -->
<edmx:Mappings>
<Mapping xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS" Space="C-S">
<Alias Key="Model" Value="GraphModel" />
<Alias Key="Target" Value="GraphModel.Store" />
<EntityContainerMapping CdmEntityContainer="GraphModelContainer" StorageEntityContainer="GraphModelStoreContainer">
<EntitySetMapping Name="LinkSet">
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Link)">
<MappingFragment StoreEntitySet="Link">
<ScalarProperty Name="Description" ColumnName="Description" />
<ScalarProperty Name="Name" ColumnName="Name" />
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToPerson)">
<MappingFragment StoreEntitySet="Link" >
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
<Condition ColumnName="LinkTypeDiscriminator" Value="1" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToLocation)">
<MappingFragment StoreEntitySet="Link" >
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
<Condition ColumnName="LinkTypeDiscriminator" Value="2" />
</MappingFragment>
</EntityTypeMapping>
</EntitySetMapping>
<EntitySetMapping Name="NodeSet">
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Node)">
<MappingFragment StoreEntitySet="Node">
<ScalarProperty Name="Description" ColumnName="Description" />
<ScalarProperty Name="Name" ColumnName="Name" />
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Person)">
<MappingFragment StoreEntitySet="Node" >
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
<Condition ColumnName="NodeTypeDiscriminator" Value="1" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Location)">
<MappingFragment StoreEntitySet="Node" >
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
<Condition ColumnName="NodeTypeDiscriminator" Value="2" />
</MappingFragment>
</EntityTypeMapping>
</EntitySetMapping>
<AssociationSetMapping Name="PersonPersonToPerson1" TypeName="GraphModel.PersonPersonToPerson1" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="Endpoint1" />
</EndProperty>
<EndProperty Name="PersonToPerson">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
<Condition ColumnName="Endpoint1" IsNull="false" />
</AssociationSetMapping>
<AssociationSetMapping Name="PersonPersonToPerson" TypeName="GraphModel.PersonPersonToPerson" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="Endpoint2" />
</EndProperty>
<EndProperty Name="PersonToPerson">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
<Condition ColumnName="Endpoint2" IsNull="false" />
</AssociationSetMapping>
<AssociationSetMapping Name="Person_PersonToLocation" TypeName="GraphModel.Person_PersonToLocation" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="Endpoint1" />
</EndProperty>
<EndProperty Name="PersonToLocation">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
<Condition ColumnName="Endpoint1" IsNull="false" />
</AssociationSetMapping>
<AssociationSetMapping Name="Location_PersonToLocation" TypeName="GraphModel.Location_PersonToLocation" StoreEntitySet="Link">
<EndProperty Name="Location">
<ScalarProperty Name="NodeId" ColumnName="Endpoint2" />
</EndProperty>
<EndProperty Name="PersonToLocation">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
<Condition ColumnName="Endpoint2" IsNull="false" />
</AssociationSetMapping>
</EntityContainerMapping>
</Mapping>
</edmx:Mappings>
</edmx:Runtime>
<!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
<edmx:Designer xmlns="http://schemas.microsoft.com/ado/2007/06/edmx">
<edmx:Connection>
<DesignerInfoPropertySet>
<DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
</DesignerInfoPropertySet>
</edmx:Connection>
<edmx:Options>
<DesignerInfoPropertySet>
<DesignerProperty Name="ValidateOnBuild" Value="true" />
</DesignerInfoPropertySet>
</edmx:Options>
<!-- Diagram content (shape and connector positions) -->
<edmx:Diagrams>
<Diagram Name="GraphModel" ZoomLevel="114" >
<EntityTypeShape EntityType="GraphModel.Node" Width="1.5" PointX="5.875" PointY="1.375" Height="1.427958984375" />
<EntityTypeShape EntityType="GraphModel.Person" Width="1.5" PointX="5.875" PointY="3.25" Height="1.4279589843749996" />
<EntityTypeShape EntityType="GraphModel.Location" Width="1.5" PointX="7.75" PointY="4.625" Height="1.0992643229166665" />
<InheritanceConnector EntityType="GraphModel.Location">
<ConnectorPoint PointX="7.375" PointY="2.0889794921875" />
<ConnectorPoint PointX="8.5" PointY="2.0889794921875" />
<ConnectorPoint PointX="8.5" PointY="4.625" />
</InheritanceConnector>
<EntityTypeShape EntityType="GraphModel.Link" Width="1.5" PointX="2.875" PointY="1.375" Height="1.427958984375" />
<EntityTypeShape EntityType="GraphModel.PersonToPerson" Width="1.75" PointX="2.625" PointY="3.125" Height="0.9349169921875" />
<InheritanceConnector EntityType="GraphModel.PersonToPerson">
<ConnectorPoint PointX="3.625" PointY="2.802958984375" />
<ConnectorPoint PointX="3.625" PointY="3.125" />
</InheritanceConnector>
<InheritanceConnector EntityType="GraphModel.Person">
<ConnectorPoint PointX="6.625" PointY="2.802958984375" />
<ConnectorPoint PointX="6.625" PointY="3.25" />
</InheritanceConnector>
<EntityTypeShape EntityType="GraphModel.PersonToLocation" Width="1.875" PointX="0.75" PointY="4.625" Height="1.2636116536458326" />
<InheritanceConnector EntityType="GraphModel.PersonToLocation">
<ConnectorPoint PointX="2.875" PointY="2.0889794921875" />
<ConnectorPoint PointX="1.65625" PointY="2.0889794921875" />
<ConnectorPoint PointX="1.65625" PointY="4.625" />
</InheritanceConnector>
<AssociationConnector Association="GraphModel.PersonPersonToPerson">
<ConnectorPoint PointX="5.875" PointY="3.8193058268229163" />
<ConnectorPoint PointX="4.375" PointY="3.8193058268229163" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.PersonPersonToPerson1">
<ConnectorPoint PointX="5.875" PointY="3.4721529134114579" />
<ConnectorPoint PointX="4.375" PointY="3.4721529134114579" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.Person_PersonToLocation">
<ConnectorPoint PointX="6.625" PointY="4.677958984375" />
<ConnectorPoint PointX="6.625" PointY="5.1875" />
<ConnectorPoint PointX="2.625" PointY="5.1875" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.Location_PersonToLocation">
<ConnectorPoint PointX="7.75" PointY="5.4791666666666661" />
<ConnectorPoint PointX="2.625" PointY="5.4791666666666661" />
</AssociationConnector>
</Diagram>
</edmx:Diagrams>
</edmx:Designer>
</edmx:Edmx>
采纳答案by Zach Burlingame
Possible Workaround
可能的解决方法
- Create a separate column for each association between derived types and make each of these columns nullable
- Create a foreign key between each of these new columns and the primary key table.
- Map each association in your Entity Model to a specific, unique column and foreign key so that each column and foreign key is only used once.
- 为派生类型之间的每个关联创建一个单独的列，并使这些列中的每一个都可以为空
- 在每个新列和主键表之间创建一个外键。
- 将实体模型中的每个关联映射到特定的唯一列和外键，以便每个列和外键仅使用一次。
Problems
问题
This is quite an undesirable solution because it explodes out the number of columns you need.
这是一个非常不受欢迎的解决方案，因为它会爆炸您需要的列数。
- More Columns- Adding a column for each association between derived types results in an explosion on the number of columns.
- Empty ColumnsIn the case of TPH, it means you'll have a lot of emptycolumns in your table.
- SQL JOIN- Switching from TPH to TPT to avoid the number of empty columns results in the necessity for EF to use a JOIN which will have to occur extremely frequently (almost every time you deal with any of the derived types).
- RefactoringIf you add a derived type in the future, you not only have to update your Entity model (*.edmx) and the it's mapping but you will also have to change the database schema by adding additional columns!
- 更多列- 为派生类型之间的每个关联添加一列会导致列数激增。
- 空列在 TPH 的情况下，这意味着您的表中将有很多空列。
- SQL JOIN- 从 TPH 切换到 TPT 以避免空列的数量导致 EF 必须使用 JOIN，这将非常频繁地发生（几乎每次处理任何派生类型时）。
- 重构如果您将来添加派生类型，您不仅需要更新实体模型 (*.edmx) 及其映射，还必须通过添加其他列来更改数据库架构！
Example
例子
For the Link/Node example above, the resulting database schema would look like this:
对于上面的链接/节点示例，生成的数据库架构如下所示：
Code
代码
SQL:
查询语句：
USE [GraphExample2]
GO
/****** Object: Table [dbo].[Node] Script Date: 02/26/2009 15:45:53 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Node](
[NodeID] [int] IDENTITY(1,1) NOT NULL,
[NodeTypeDiscriminator] [int] NOT NULL,
[Name] [varchar](255) NOT NULL,
[Description] [varchar](1023) NULL,
CONSTRAINT [PK_Node] PRIMARY KEY CLUSTERED
(
[NodeID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object: Table [dbo].[Link] Script Date: 02/26/2009 15:45:53 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Link](
[LinkID] [int] IDENTITY(1,1) NOT NULL,
[LinkTypeDiscriminator] [int] NOT NULL,
[LeaderID] [int] NULL,
[FollowerID] [int] NULL,
[PersonID] [int] NULL,
[LocationID] [int] NULL,
[Name] [varchar](255) NULL,
[Description] [varchar](1023) NULL,
CONSTRAINT [PK_Link] PRIMARY KEY CLUSTERED
(
[LinkID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object: ForeignKey [FK_Link_Node_Follower] Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Follower] FOREIGN KEY([FollowerID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Follower]
GO
/****** Object: ForeignKey [FK_Link_Node_Leader] Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Leader] FOREIGN KEY([LeaderID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Leader]
GO
/****** Object: ForeignKey [FK_Link_Node_Location] Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Location] FOREIGN KEY([LocationID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Location]
GO
/****** Object: ForeignKey [FK_Link_Node_Person] Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link] WITH CHECK ADD CONSTRAINT [FK_Link_Node_Person] FOREIGN KEY([PersonID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Person]
GO
EDMX:
EDMX：
<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
<!-- EF Runtime content -->
<edmx:Runtime>
<!-- SSDL content -->
<edmx:StorageModels>
<Schema Namespace="GraphModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
<EntityContainer Name="GraphModelStoreContainer">
<EntitySet Name="Link" EntityType="GraphModel.Store.Link" store:Type="Tables" Schema="dbo" />
<EntitySet Name="Node" EntityType="GraphModel.Store.Node" store:Type="Tables" Schema="dbo" />
<AssociationSet Name="FK_Link_Node_Follower" Association="GraphModel.Store.FK_Link_Node_Follower">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
<AssociationSet Name="FK_Link_Node_Leader" Association="GraphModel.Store.FK_Link_Node_Leader">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
<AssociationSet Name="FK_Link_Node_Location" Association="GraphModel.Store.FK_Link_Node_Location">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
<AssociationSet Name="FK_Link_Node_Person" Association="GraphModel.Store.FK_Link_Node_Person">
<End Role="Node" EntitySet="Node" />
<End Role="Link" EntitySet="Link" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Link">
<Key>
<PropertyRef Name="LinkID" />
</Key>
<Property Name="LinkID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="LinkTypeDiscriminator" Type="int" Nullable="false" />
<Property Name="LeaderID" Type="int" />
<Property Name="FollowerID" Type="int" />
<Property Name="PersonID" Type="int" />
<Property Name="LocationID" Type="int" />
<Property Name="Name" Type="varchar" MaxLength="255" />
<Property Name="Description" Type="varchar" MaxLength="1023" />
</EntityType>
<EntityType Name="Node">
<Key>
<PropertyRef Name="NodeID" />
</Key>
<Property Name="NodeID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="NodeTypeDiscriminator" Type="int" Nullable="false" />
<Property Name="Name" Type="varchar" Nullable="false" MaxLength="255" />
<Property Name="Description" Type="varchar" MaxLength="1023" />
</EntityType>
<Association Name="FK_Link_Node_Follower">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="FollowerID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Link_Node_Leader">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="LeaderID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Link_Node_Location">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="LocationID" />
</Dependent>
</ReferentialConstraint>
</Association>
<Association Name="FK_Link_Node_Person">
<End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
<End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
<ReferentialConstraint>
<Principal Role="Node">
<PropertyRef Name="NodeID" />
</Principal>
<Dependent Role="Link">
<PropertyRef Name="PersonID" />
</Dependent>
</ReferentialConstraint>
</Association>
</Schema>
</edmx:StorageModels>
<!-- CSDL content -->
<edmx:ConceptualModels>
<Schema xmlns="http://schemas.microsoft.com/ado/2006/04/edm" Namespace="GraphModel" Alias="Self">
<EntityContainer Name="GraphModelContainer" >
<EntitySet Name="NodeSet" EntityType="GraphModel.Node" />
<EntitySet Name="LinkSet" EntityType="GraphModel.Link" />
<AssociationSet Name="PersonPersonToPerson_Leader" Association="GraphModel.PersonPersonToPerson_Leader">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToPerson" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="PersonPersonToPerson_Follower" Association="GraphModel.PersonPersonToPerson_Follower">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToPerson" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="Person_PersonToLocation" Association="GraphModel.Person_PersonToLocation">
<End Role="Person" EntitySet="NodeSet" />
<End Role="PersonToLocation" EntitySet="LinkSet" />
</AssociationSet>
<AssociationSet Name="Location_PersonToLocation" Association="GraphModel.Location_PersonToLocation">
<End Role="Location" EntitySet="NodeSet" />
<End Role="PersonToLocation" EntitySet="LinkSet" />
</AssociationSet>
</EntityContainer>
<EntityType Name="Node" Abstract="true">
<Key>
<PropertyRef Name="NodeId" />
</Key>
<Property Name="NodeId" Type="Int32" Nullable="false" />
<Property Name="Name" Type="String" Nullable="false" />
<Property Name="Description" Type="String" Nullable="true" />
</EntityType>
<EntityType Name="Person" BaseType="GraphModel.Node" >
<NavigationProperty Name="Leaders" Relationship="GraphModel.PersonPersonToPerson_Leader" FromRole="Person" ToRole="PersonToPerson" />
<NavigationProperty Name="Followers" Relationship="GraphModel.PersonPersonToPerson_Follower" FromRole="Person" ToRole="PersonToPerson" />
<NavigationProperty Name="Locations" Relationship="GraphModel.Person_PersonToLocation" FromRole="Person" ToRole="PersonToLocation" />
</EntityType>
<EntityType Name="Location" BaseType="GraphModel.Node" >
<NavigationProperty Name="Visitors" Relationship="GraphModel.Location_PersonToLocation" FromRole="Location" ToRole="PersonToLocation" />
</EntityType>
<EntityType Name="Link" Abstract="true">
<Key>
<PropertyRef Name="LinkId" />
</Key>
<Property Name="LinkId" Type="Int32" Nullable="false" />
<Property Name="Name" Type="String" Nullable="true" />
<Property Name="Description" Type="String" Nullable="true" />
</EntityType>
<EntityType Name="PersonToPerson" BaseType="GraphModel.Link" >
<NavigationProperty Name="Leader" Relationship="GraphModel.PersonPersonToPerson_Leader" FromRole="PersonToPerson" ToRole="Person" />
<NavigationProperty Name="Follower" Relationship="GraphModel.PersonPersonToPerson_Follower" FromRole="PersonToPerson" ToRole="Person" />
</EntityType>
<EntityType Name="PersonToLocation" BaseType="GraphModel.Link" >
<NavigationProperty Name="Person" Relationship="GraphModel.Person_PersonToLocation" FromRole="PersonToLocation" ToRole="Person" />
<NavigationProperty Name="Location" Relationship="GraphModel.Location_PersonToLocation" FromRole="PersonToLocation" ToRole="Location" />
</EntityType>
<Association Name="PersonPersonToPerson_Leader">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
</Association>
<Association Name="PersonPersonToPerson_Follower">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
</Association>
<Association Name="Person_PersonToLocation">
<End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
<End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
</Association>
<Association Name="Location_PersonToLocation">
<End Type="GraphModel.Location" Role="Location" Multiplicity="1" />
<End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
</Association>
</Schema>
</edmx:ConceptualModels>
<!-- C-S mapping content -->
<edmx:Mappings>
<Mapping xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS" Space="C-S">
<Alias Key="Model" Value="GraphModel" />
<Alias Key="Target" Value="GraphModel.Store" />
<EntityContainerMapping CdmEntityContainer="GraphModelContainer" StorageEntityContainer="GraphModelStoreContainer">
<EntitySetMapping Name="LinkSet">
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Link)">
<MappingFragment StoreEntitySet="Link">
<ScalarProperty Name="Description" ColumnName="Description" />
<ScalarProperty Name="Name" ColumnName="Name" />
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToPerson)">
<MappingFragment StoreEntitySet="Link" >
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
<Condition ColumnName="LinkTypeDiscriminator" Value="1" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToLocation)">
<MappingFragment StoreEntitySet="Link" >
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
<Condition ColumnName="LinkTypeDiscriminator" Value="2" />
</MappingFragment>
</EntityTypeMapping>
</EntitySetMapping>
<EntitySetMapping Name="NodeSet">
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Node)">
<MappingFragment StoreEntitySet="Node">
<ScalarProperty Name="Description" ColumnName="Description" />
<ScalarProperty Name="Name" ColumnName="Name" />
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Person)">
<MappingFragment StoreEntitySet="Node" >
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
<Condition ColumnName="NodeTypeDiscriminator" Value="1" />
</MappingFragment>
</EntityTypeMapping>
<EntityTypeMapping TypeName="IsTypeOf(GraphModel.Location)">
<MappingFragment StoreEntitySet="Node" >
<ScalarProperty Name="NodeId" ColumnName="NodeID" />
<Condition ColumnName="NodeTypeDiscriminator" Value="2" />
</MappingFragment>
</EntityTypeMapping>
</EntitySetMapping>
<AssociationSetMapping Name="PersonPersonToPerson_Follower" TypeName="GraphModel.PersonPersonToPerson_Follower" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="FollowerID" />
</EndProperty>
<EndProperty Name="PersonToPerson">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
</AssociationSetMapping>
<AssociationSetMapping Name="PersonPersonToPerson_Leader" TypeName="GraphModel.PersonPersonToPerson_Leader" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="LeaderID" />
</EndProperty>
<EndProperty Name="PersonToPerson">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
</AssociationSetMapping>
<AssociationSetMapping Name="Person_PersonToLocation" TypeName="GraphModel.Person_PersonToLocation" StoreEntitySet="Link">
<EndProperty Name="Person">
<ScalarProperty Name="NodeId" ColumnName="PersonID" />
</EndProperty>
<EndProperty Name="PersonToLocation">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
</AssociationSetMapping>
<AssociationSetMapping Name="Location_PersonToLocation" TypeName="GraphModel.Location_PersonToLocation" StoreEntitySet="Link">
<EndProperty Name="Location">
<ScalarProperty Name="NodeId" ColumnName="LocationID" />
</EndProperty>
<EndProperty Name="PersonToLocation">
<ScalarProperty Name="LinkId" ColumnName="LinkID" />
</EndProperty>
</AssociationSetMapping>
</EntityContainerMapping>
</Mapping>
</edmx:Mappings>
</edmx:Runtime>
<!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
<edmx:Designer xmlns="http://schemas.microsoft.com/ado/2007/06/edmx">
<edmx:Connection>
<DesignerInfoPropertySet>
<DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
</DesignerInfoPropertySet>
</edmx:Connection>
<edmx:Options>
<DesignerInfoPropertySet>
<DesignerProperty Name="ValidateOnBuild" Value="true" />
</DesignerInfoPropertySet>
</edmx:Options>
<!-- Diagram content (shape and connector positions) -->
<edmx:Diagrams>
<Diagram Name="GraphModel" ZoomLevel="114" >
<EntityTypeShape EntityType="GraphModel.Node" Width="1.5" PointX="5.875" PointY="1.375" Height="1.427958984375" />
<EntityTypeShape EntityType="GraphModel.Person" Width="1.5" PointX="5.875" PointY="3.25" Height="1.4279589843749996" />
<EntityTypeShape EntityType="GraphModel.Location" Width="1.5" PointX="7.75" PointY="4.625" Height="1.0992643229166665" />
<InheritanceConnector EntityType="GraphModel.Location">
<ConnectorPoint PointX="7.375" PointY="2.4176741536458342" />
<ConnectorPoint PointX="8.5" PointY="2.4176741536458342" />
<ConnectorPoint PointX="8.5" PointY="4.625" />
</InheritanceConnector>
<EntityTypeShape EntityType="GraphModel.Link" Width="1.5" PointX="2.875" PointY="1.375" Height="1.427958984375" />
<EntityTypeShape EntityType="GraphModel.PersonToPerson" Width="1.75" PointX="2.75" PointY="3.25" Height="1.2636116536458326" />
<InheritanceConnector EntityType="GraphModel.PersonToPerson" ManuallyRouted="false">
<ConnectorPoint PointX="3.625" PointY="2.802958984375" />
<ConnectorPoint PointX="3.625" PointY="3.25" />
</InheritanceConnector>
<InheritanceConnector EntityType="GraphModel.Person">
<ConnectorPoint PointX="6.625" PointY="3.4603483072916683" />
<ConnectorPoint PointX="6.625" PointY="3.25" />
</InheritanceConnector>
<EntityTypeShape EntityType="GraphModel.PersonToLocation" Width="1.875" PointX="0.75" PointY="4.625" Height="1.2636116536458326" />
<InheritanceConnector EntityType="GraphModel.PersonToLocation">
<ConnectorPoint PointX="2.875" PointY="2.4176741536458342" />
<ConnectorPoint PointX="1.65625" PointY="2.4176741536458342" />
<ConnectorPoint PointX="1.65625" PointY="4.625" />
</InheritanceConnector>
<AssociationConnector Association="GraphModel.PersonPersonToPerson_Leader">
<ConnectorPoint PointX="5.875" PointY="3.8818058268229163" />
<ConnectorPoint PointX="4.5" PointY="3.8818058268229163" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.PersonPersonToPerson_Follower">
<ConnectorPoint PointX="5.875" PointY="3.5034029134114579" />
<ConnectorPoint PointX="4.5" PointY="3.5034029134114579" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.Person_PersonToLocation">
<ConnectorPoint PointX="6.625" PointY="4.677958984375" />
<ConnectorPoint PointX="6.625" PointY="5.0078214863281243" />
<ConnectorPoint PointX="2.625" PointY="5.0078214863281243" />
</AssociationConnector>
<AssociationConnector Association="GraphModel.Location_PersonToLocation">
<ConnectorPoint PointX="7.75" PointY="5.40018798828125" />
<ConnectorPoint PointX="2.625" PointY="5.40018798828125" />
</AssociationConnector>
</Diagram>
</edmx:Diagrams>
</edmx:Designer>
</edmx:Edmx>
回答by Salahuddin Khan
AoA!
啊！
EntityModelCodeGenerator create 0..1 to manyrelation between two tables, Make it 1 to many.
EntityModelCodeGenerator在两个表之间创建0..1 to many关系，使其成为1 to many。
In this kind of case it may be a possible Solution.
在这种情况下，它可能是一个可能的解决方案。
Best Regards! Salahuddin
此致！沙拉胡丁
回答by Jerry Nixon
I had this error and it indicated that a column I removed in the database had not been removed in the model. I removed it from the model and the error went away. That was mysituation, though. Maybe it will help someone.
我有这个错误，它表明我在数据库中删除的一列没有在模型中删除。我从模型中删除了它，错误消失了。不过，这就是我的情况。也许它会帮助某人。
